AR and androgen insensitivity syndrome: Global loss of AR function mutants in XY individuals, including testicular feminization mutation (Tfm), androgen receptor knock-out (ARKO) and complete androgen insensitivity syndrome (cAIS) patients have a comparable phenotype [29, 30], matching growth rates to wild-type XX individuals in young adulthood then drastic development of obesity in later adulthood [31–34].